Villagers made offerings of vegetables and meat at the crater's edge in an attempt to prevent further explosions.

Meanwhile, in the far northwest of the country, a second volcano, Mount Awu, was rocked by a series of small blasts, adding to the fears of 12,000 villagers already evacuated from its slopes to a nearby town.

Officials at Mount Bromo on the country's main island of Java said it was possible that several hikers may still be on its slopes - either alive or dead - after Tuesday's explosion.

The blast sent a smoke cloud 3,000m into the sky. One of the dead was a Malaysian hiker, the other was an Indonesian. Five people were injured.

Witnesses said dozens of rescuers searched the volcano's scorched slopes and lower jungle tracks, but by mid-afternoon they had found no survivors.

The 2,329m peak was still rumbling and spewing smoke, but in much less volume than on yesterday.

Bromo, 700km east of Jakarta, is in a national park and is often scaled by foreign tourists. Authorities closed the park to visitors.

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Several villagers from Ngaden Sari village, about 1km from the top of the mountain, went to the summit and hurled offerings including cooked chicken, vegetables and soybeans into its crater.

"We hope to stop Mount Bromo from erupting again," said one villager who took part in the ceremony, regularly performed when the mountains shows signs of activity.

After an hour at the crater, rescue officials ordered the group to return home.

In northeastern Indonesia, several small explosions rocked Mount Awu, said Samuel Delompaha, a government seismographer in Tahuna, a town close to the mountain on Sangihe island.

About 12,000 evacuees are sheltering in government offices and schools in the town, about 2,160km north-east of Jakarta.

Officials have set up emergency medical centers and distributed food and blankets in several places on the island, which lies just south of the Philippines.

Authorities ordered the evacuation last week, and have said a major eruption is possible in the coming days.

Regional district head Yopi Kakondo said many people in the town were afraid, especially those too young to remember the mountain's last major eruption in 1966, which killed 40 people.

"For people of my generation it is not so bad, however," he said.

"It doesn't look as bad as 66 from here."

Indonesia straddles the geologically active Pacific Ring of Fire and has at least 100 active volcanoes - more than any other country in the world.